Search Results

Some new vehicle ride vibration data are presented. The Janeway recommended limit, Pradko/Lee absorbed power, and Mil-Std-1472A (proposed ISO tolerance criteria) provide formats for the data presentation. A brief literature review of the subjective tolerance question is included. The importance of seating systems which attenuate vehicle vibration is demonstrated.

Ten points are offered as essential to good adhesives joint design. Examples of the role of adhesives in current Army hardware such as the LAW and Shillelagh antitank missiles and the Airmobile Aircraft Maintenance Shop are discussed. Training requirements are outlined for personnel who are to bond munitions with adhesives, and examples of process controls for production line assembly are given.

This paper presents information on Navy research and development programs dealing with adhesives and adhesive bonding, with respect to their objectives, approach, findings, and future efforts. Three specific areas are singled out for discussion: stress corrosion failure of bonded aluminum; adhesives for use with difficulty bonded nonmetallic surfaces (polymers) and rocket propellants; and bonding and joining techniques for advanced filamentary graphite composites. Stress corrosion experimentation demonstrated the accumulation of corrosion products on the exposed aluminum. It is suggested that the diffusion of polyamine from epoxide adhesives contributes to the accelerated corrosion which leads to the formation of weak boundary layers. A proposed mechanism for stress corrosion cracking is presented. Forty standard adhesives of 26 types were investigated in the study of difficultly bonded surfaces and rocket propellant.

Three engine camshaft approaches to the reduction of oxides of nitrogen were investigated: increased valve overlap, variable camshaft timing, and variable valve overlap. The interaction of these systems with emissions, fuel consumption, and power was evaluated on a dynamometer engine. The effects of air-fuel ratio and exhaust backpressure were also reported. Results of the dynamometer study were verified with vehicle tests. Oxides of nitrogen levels of 1.2-2.0 g/mile were attained through camshaft design with acceptable drivability on the 1970 federal test procedure.

Research has been done on preignition in automotive engines using a new experimental method enabling the phenomenon to be followed from its onset to its final phase. The technique consists of interrupting conventional spark ignition for a brief period and detecting any uncontrolled ignition signal at no matter what instant in the cycle it may occur. With regard to the danger of preignition, it was demonstrated that fuel effect depends on the following two properties: specific resistance to hot-point ignition and capacity to heat up a possible ignition source. The latter characteristic is linked to both combustion speed and fuel flame temperature. The source of preignition is usually the exhaust valve covered with mineral deposits coming from fuel and lubricant additives. The most harmful deposits are made of barium and calcium phosphates coming from detergent additives in lubricants; whereas lead compounds coming from antiknock additives in fuels have no appreciable effect.

Instantaneous gas velocities inside the combustion chamber, cylinder and inlet port of a motored 4-stroke engine have been determined using a constant-temperature hot wire anemometer. The measurements were made with both stationary and moving probes, the latter being operated by means of a traversing mechanism driven from the piston of an adjoining cylinder. With the moving probes, it was possible to study the flow close to the piston crown throughout the induction stroke. The probes were calibrated in a steady gas stream and their response checked under transient conditions using a shock tube. Cylinder gas flow readings were obtained at two speeds of rotation of the engine and a masked inlet valve was used to create varying degrees of induction swirl.

NEW TIRE STUD DEVELOPMENTS Although they offer snowbelt motorists substantial improvement of vehicle control on icy roads, studded tires have been attacked with increasing vigor by highway officials for their contribution to road wear. Tests of some recently developed tire stud designs show promise that the safety and convenience factors of studded tires can be retained -- but with a considerable reduction in the amount of road wear caused by their use. In addition to a reduction in weight and minor dimensional changes, most of these new tire studs are designed in such a way that the carbide pin will move further into the stud body if, at any time, the protrusion of the stud from the tire exceeds a critical limit. (The greater the protrusion, the greater the impact force. And it is high impact force which causes the road wear.) With their built-in protrusion-adjustment capability, the new tire studs maintain nearly uniform protrusion throughout their lifetime.

Increasing winter abrasion of pavement surfaces led the 1969 Minnesota Legislature to order the Minnesota Highway Department to conduct an in-depth study of studded tire effects relating to pavement wear and safety. In the laboratory, studded tires without sand and salt abraded pavement specimens 100 times faster than unstudded tires with sand and salt. Laboratory wear rates correlated with those found on highway pavements. If pavement wear should continue to increase at the same rate, premature repairs would become necessary at great cost. Accident studies indicated that on icy and snowy roads studded tires provide slight advantage over snow tires, but it was considered unlikely that discontinuance of studded tires would make an appreciable change in traffic safety in Minnesota.

In September 1971, Anderson Power Products decided to design an electric highway vehicle scheduled for production by July 1972. The production design was based on two previous prototype vehicles. All the vehicles were original designs based on the unique requirements of battery-powered systems. This paper discusses a systems concept for electric vehicles, the design and evolution of a third-generation vehicle, and the support equipment necessary for successful vehicle operation and maintenance.

Proper selection of the traction drive system to meet the requirements of an electric passenger vehicle is of prime importance. Choice may be made among alternating current, direct current or combined systems. Each approach can be implemented by utilizing various control techniques and power elements. For instance, an AC system may use an adjustable voltage inverter (AVI) or a pulse-width-modulated inverter (PWMI) for the power processor; and an induction motor or a synchronous motor for the rotating element. Similar alternatives exist for a DC system. The choice of a suitable manner of implementation must be based on information characterizing the various elements and tradeoffs matching them to the vehicle requirements. This paper describes various AC and DC techniques, characterizes AVI, PWM and representative DC chopper power processors and examines their interface with a variety of motors such as series, shunt, induction, etc.

Experimental measurements of the instantaneous exhaust gas temperature, mass flowrate, and hydrocarbon concentration have been made in the exhaust of a single cylinder research engine. The temperature measurements were accomplished using an infrared optical technique and observing the radiation of the exhaust gas at the 4.4 μm band of CO2. Instantaneous exhaust gas mass flowrates were monitored by placing a restriction in the exhaust manifold and measuring the instantaneous pressures across the restriction. Time-resolved hydrocarbon concentrations were measured using a fast-acting sampling valve with an open time of 2 ms. From these measurements, the hydrocarbon mass flowrate is calculated as a function of crank angle.

The gas-phase exhaust emissions which resulted when a variably timed, variable mass of water was injected directly into the cylinder of a spark-ignition engine are reported. The experimental setup and the procedure used in the investigation are also described. Conclusions are drawn with regard to the optimum injection timing and amount of water introduced. Generally, direct-cylinder injection of water reduces NO, increases unburned HC, and does not effect CO and CO2. For a fixed-ignition timing, power also deteriorates. Another finding of this investigation is that direct-cylinder injection does result in NO reductions of better than 85% while using about one-third the mass of water required by manifold injection to effect a similar reduction.

The purpose of this paper is to describe the recent development by GMC, of an over-the-highway 34,000# tandem rear axle air suspension system for heavy duty truck/tractor applications. Various design approaches for truck air suspensions during the past two decades, are touched upon to trace the evolution process leading to the present design philosophy which provides roll resistance comparable to steel leaf spring suspension systems.

Requirements and constraints for rapid charging batteries used for both pulse load and deep cycle service are outlined. Methods for fast recharging nickel-cadmium and lead acid batteries are described. A new rapid charge concept wherein nickel-cadmium batteries are both rapid charged and reconditioned is presented. Similarly, a unique method of fast charging lead acid batteries is described and illustrated. Areas of required technology improvements in batteries and electronic control devices for rapid charge application are outlined.

Over the past decade, significant areas of power semiconductor development have been: Increased electrical performance characteristics and optimization of the mix of same to meet specific application requirements. Improved packaging for better heat management and lower system cost. Thoughtful rating and characterization of devices specifically tailored to the needs of the control equipment designer. These developments, as would be expected, have precipated the wide acceptance and usage of power semiconductors in diverse areas of power control. The resultant benefit has been an ever improving system performance at a decreasing system cost.

As manufacturers of air-cooled diesel engines, the company of Klöckner-Humboldt-Deutz (KHD) undertook the rather rapid development of a multifuel engine on the basis of a proved mass-produced, air-cooled unit. Being equal in output, this new engine had to run on all fuels and fuel mixtures obtainable at gasoline stations without any modifications being necessary. Preferably, it had to be produced by means of the same manufacturing facilities as the series engine and features a maximum number of identical parts. The solution to the problem involves supplementing the series engine with a high-tension ignition system employing a special spark plug in the direct vicinity of the injection nozzle. This spark plug can be subsequently installed following the rework of standard parts. By using the same basic setting of injection and ignition for all fuels, it is possible to attain absolutely knock-free combustion, with a gentle compression curve and a minimum of cyclic pressure variations.

This paper describes and discusses the results obtained from tests of the effect of air swirl variations on smoke and gaseous emissions from direct-injection-type diesel engines. Within the limits of the swirl variations used, an increase in swirl reduced emissions of smoke and carbon monoxide but increased nitric oxide emissions. An increase in swirl also makes it possible to retard appreciably the injection timing for optimum engine efficiency, and this more than compensates for the increase in nitric oxide emission due to the increase in swirl. It is also shown that the air swirl intervenes in the processes of smoke and gaseous pollutant formation by affecting the details of the fuel-air mixing processes.

A Coordinating Research Council cooperative program was conducted to evaluate the measurement methods used to analyze nitric oxide and carbon monoxide in diesel exhaust. Initially, a single-cylinder test engine was circulated among participants with poor results. Tests were then conducted at one site using a multicylinder diesel engine. Six organizations participated in the program. Exhaust analyses were conducted at steady-state engine conditions and on a 3 min cycle test. Span gases of unknown concentration were also analyzed. The participants results varied but averaged less than ±5% standard deviation both within (repeatability) and among (reproducibility) the instruments. The short cycle test was in good agreement with the steady-state measurements. No significant difference in the use of Drierite, nonindicating Drierite, or Aquasorb desiccants was evident in sampling system tests.

There are many flow problems in which the flow quantity in a short, irregular duct must be measured. A measurement technique which is fast, causes no pressure loss, and can tolerate poor flow quality is often needed. The flow through the radiator duct of a wind tunnel model is one example. Four sensors were tested for velocity response and sensitivity to duct geometry. A full-factorial experiment utilizing a modular simulation of a radiator duct was employed. Two sensors, a propeller anemometer and a long hot wire, seemed to be quite independent of velocity distribution and flow angularity.

In the development of high-speed automotive vehicles, wind resistance and vehicle stability characteristics, particularly aerodynamic lift and side-force effects, must be better understood. For this purpose and other uses, the Nissan Motor Co. has constructed a new full-scale wind tunnel now in operation at its Oppama Proving Ground. The new wind tunnel has been used for experimental studies of the factors contributing to the aerodynamic characteristics of passenger car bodies, and the results are described herein. The authors have also clarified the relationship between aerodynamic characteristics and high-speed road performance. The effect of minor changes in car shape, with various attachments, has been investigated. Finally, the principle of a rear spoiler is treated both theoretically and experimentally at some length.